Participants are asked to form "if-then" plans and the instructions are presented in the first person ("if I...then I..."). "Ifs" are critical situations, "thens" are appropriate responses.

Participants are asked to form "if-then" plans and the instructions are presented in the second person ("if you...then you..."). "Ifs" are critical situations, "thens" are appropriate responses.

Participants are presented with "ifs "(critical situations) and "thens" but are not asked to form "if-then" plans.

"If-then" plans (or "implementation intentions") involve linking in memory critical situations (e.g., temptations) with appropriate responses (e.g., substitution)

The main outcome measure was adapted from the Pittsburgh Sleep Quality Index (Buysse, Reynolds, Monk, Berman, & Kupfer, 1989), and was designed to tap both quantity and quality of sleep. Sleep quantity was assessed by asking: "How many hours of actual sleep do you normally get on a night before school? _________ hours," "What time do you normally go to bed on a night before school? __________ pm," and "What time do you normally get up on a school day? __________ am."

Sniehotta, Nagy, and Scholz's (2006) six items were used to capture three facets of action control (Karoly, 1993) on 7-point (+1 to +7) strongly disagree-strongly agree scales. (e.g., "During the last month I constantly monitored my sleep on the nights before school")